Evaluating different additive levels of yeast, Saccharomyces cerevisiae, on the growth and production performances of a hybrid of two populations of Egyptian African catfish, Clarias gariepinus

A breeding and feeding experiment was undertaken to study the performances of the hybrid of two Egyptian populations of African catfish Clarias gariepinus, El-Manzalah catfish (MCF) characterized by the tolerance against poor water quality and the ease to be farmed in captivity and El-Qanater catfish (QCF) characterized by rapid growth and high quality flesh. Crosses of these two populations (MCF♀ × QCF♂) were carried out in El-Gamalia hatchery, El-Manzalah, Egypt, during spring. When the mean body weight of African catfish hybrid fingerlings has reached 24.34 ± 1.38 g (mean ± SD) they were transferred to cages (112 m3) with a stocking density of 50 fish/m3 suspended in lake El-Manzalah. Fish were fed a formulated diet containing approximately 31% (analyzed value) crude protein and cultured for 214 days. Four levels of dried brewer's yeast, Saccharomyces cerevisiae, (DY) were used as feed additives at levels of 0.0, 1.0, 1.5 and 2.0% in diets. Results showed that, adding high level of DY, 2%, recorded highest final body weight (913.26 g), growth rate (4.72 g/fish/day), total production (47.5 kg/m3) and profit per cage (52.21%) after 186 days. The study demonstrates that DY inclusion in the feeds of hybrid cat fish was significant. However, finding the optimal inclusion level of DY still needs more investigation of higher DY levels than 2%.The overall data of the present study has confirmed that catfish hybrid showed better parameters than the parents in respect of growth rate, survival percentage and feed efficiency. Moreover, hybrid catfish had a significantly highest production, 47.5 kg/m3.